This is not ArchLinux' fuckup. The AUR's popularity exploded after certain Arch-based distros (and software) decided to treat the AUR as an additional software repository, even part of package management, and automate the process of installation. Which also slows the process of discovering the malware. And makes panicky users wave their arms.

May I remind everyone of Arch core principles and statements wrt AUR - several quotes from their wiki:

Whereas many GNU/Linux distributions attempt to be more user-friendly, Arch Linux has always been, and shall always remain user-centric:

• The distribution is intended to fill the needs of those contributing to it, rather than trying to appeal to as many users as possible.
• It is targeted at the proficient GNU/Linux user, or anyone with a do-it-yourself attitude who is willing to read the documentation, and solve their own problems.

The Arch User Repository (AUR) is a community-driven repository for Arch Linux users. It contains package descriptions (PKGBUILDs) that allow you to compile a package from source with makepkg and then install it via pacman.

Note how the crucial PKGBUILD is mentioned in the first sentence, and dozens of times in the article that follows.

Warning
AUR helpers are not supported by Arch Linux. You should become familiar with the manual build process in order to be prepared to troubleshoot problems.

The AUR even includes PGP signing; not perfect, but a useful additional step. But, alas, many AUR helpers include "skip PGP check".

Archlinux devs, maintainers and users have been saying this for over a decade, and warning against using the AUR in such ways. But short of shutting the whole thing down, what can they do? The few things that can reasonably be done I'm sure are being implemented right now.

I wouldn't really categorise it as a fuckup. These are unofficial packages from the AUR. You should trust them as much as random install scripts from a no-name website or git repo.